Automatic drop hammer for soil test boring



Sept. 13,-1960 s. URBAN 2,952,132

AUTOMATIC DROP HAMMER FOR SOIL. TEST BORING Filed July 5, 1956 United States Patent O g Y 2,952,132 AUTOMATIC DROP HAMMER FoR sonJ TEST BORING .Stephen Urban, 926 5th Ave., New York, N.Y.

Filed July 5, 1956, Ser. No. 595,876

1 Claim. (Cl. 6173) This invention relates to mechanical hammers and, more particularly, to power operated drop hammers for soil test boring.

Heretofore, various types of hammer devices have been used in connection with soil test borings, pile driving, Well drilling operations, and the like. However, because of variations in the regularity of the hammer blows and the introduction of various errors by the operator, the speed, accuracy, and general dependability of these devices have varied. An object of this invention, therefore, is to provide an automatic drop hammer assembly that is simple in construction, efficient in operation, and lwhich will overcome all of the aforementioned difficulties.

Still another object of this invention, is to provide an automatic drop hammer particularly suitable for soil test boring that provides precision drop height and drop Weight, regularity of hammer blows and the elimination of operator introduced errors.

All of the foregoing and still further objects and advantages of this invention will become apparent from the following specification, taken in connection with the accompanying drawing, wherein:

Figure 1 is a side view of a drop hammer assembly made in accordance with this invention shown with the hammer in a descending position;

Figure 2 is a fragmentary view of Figure 1 showing the hammer being lifted; and

Figure 3 is a cross-sectional view taken along line 3-3 of Figure 1.

Referring now to Figure 1 of the drawing, a drop hammer made in accordance with this invention is shown to include a ground engaging base having a pair of angularly and inwardly inclined side arms 11 that are adapted to support a vertical hammer assembly 12 therebetween. As more clearly shown in Figure 3, the hammer assembly 12 includes a pair of spaced, vertical, channel lmembers 14, 15, each of which has a pair of inwardly extending angle members 16, 17, respectively. These angle members 16, 17, define channels for slidably receiving the side rails 18, 19, of the vertically disposed hammer shaft 20 that operatively supports the hammer head 21 at its lower extremity. One side of the shaft 20 is provided with a vertical, longitudinally extending groove 22 that slidably receives an elongated rack gear 2.3, having a plurality of longitudinally spaced teeth 24. The gear 23 is maintained in engagement with the shaft 20 by means of a pair of guide and securing plates 26, 27, that are secured to the shaft 20 and are slidably received within matching grooves 28, 29, in the sides of the rack gear 23. The rack gear 23 is spring biased in both longitudinal directions by means of springs that act at each longitudinal extremity thereof. As more clearly shown in Figure 2, an upper compression spring 30 reacts against a shoulder 32 formed at the upper end of the hammer shaft 20 at one end and abuts the upper end of the rack gear 23 at its other end. Similarly, a lower compression spring 31 reacts between the lower shoulder 33 and the lower end of the rack gear 23.

2,952,132 ce Pafniea sept. 13, 1960 An actuator assembly 40 is operatively supported on the supporting frame adjacent to the rack gear assembly. A motor 41 is supported on a horizontal platform carried by the side arms 11 and reinforced by a gusset 43. An;

idler shaft assembly 45 driven by the motor through'a gage the teeth 24 of the rack gear.

In operation, the motor is energized whereupon the sector gear 48 is continuously rotated in a clockise direction so as to intermittently engage the teeth 24 of the rack gear. As the gear 48 rotates in the clockwise direction as viewed in Figure 2, the rack gear is urged upwardly against the action of the upper spring 30 until it is fully compressed, whereupon the entire hammer shaft 20 is raised, thereby lifting the attached hammer shaft 21. When the blank part of the gear 48 approaches the rack gear, the entire hammer shaft 20 is caused to drop by gravity so that upon impact, the rack gear 23 continues downwardly against the reaction of the lower spring 31, compressing the spring which then lifts the rack gear 23 vertically, and after which the first teeth 50 of the gear sector 48 again approach the teeth 24 of the rack gear and engage therewith so as to continue the lifting movement of the entire shaft 20, as described. Because of the spring support of the rack gear, impact shocks at both eXtremities are absorbed, thereby also reducing stress on the gear teeth during the initial lifting engagement. It will, therefore, be recognized that due to the action of the upper and lower springs 30, 31, the gear rack bounces back and forth which reciprocating movement facilitates the engagement of the first tooth of the sector gear in a self-locating full tooth grip.

While this invention has been described with particular reference to the particular form shown in the drawing, it is to be understood that such is not to be construed as imparting limitations upon the invention, which is best defined by the claim appended hereto.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

A mechanical hammer comprising, in combination, a base frame, a vertical hammer assembly having a vertical shaft supported for reciprocating vertical movement upon said frame, motor means carried by said frame for driving said hammer assembly, a vertical rack gear supported for reciprocating vertical movement upon said vertical shaft, a first compression spring seat at opposite ends between the upper extremity of said vertical shaft and the upper extremity of said vertical rack gear yieldably resisting relative movement between said vertical shaft and said vertical gear in one direction, a second compression spring seated at opposite ends between the lower eXtremity of said vertical shaft and the lower extremity vof said vertical gear yieldably resisting relative movement between said vertical shaft and said vertical gear in an opposite direction, said motor means drivingly engaging said vertical rack gear, said motor means comprising a drive shaft, a second gear secured to said drive shaft for rotation Within a plane common to a plane containing the teeth of said rack gear, said sector gear having a toothed portion with teeth rotatable into the path of movement of said rack gear for meshing engagement therewith during a portion of each yrevolution of said drive shaft, said sector gear releasing said rack gear during the other portion of each revolution of said drive shaft, whereby continuous rotation `of said sector gear in a single direction is operative to elevate said rack gea-r during the rst mentioned portion of each revolution of said drive shaft, upward movement of said rack gear being operative compressing said first compression spring acting between said upper extremities of said vertical shaft and said vertical rack gear to elevate said vertical shaft, and

' disengagement of said rack gear during the second men tioned portionr of eachr revolution of said drive shaft allowing said rack gear and vertical shaft to drop by gravity into striking engagement with awork piece, `downward movement of saidrack gear relative to's'aid vertical References Cited in the file of this paten UNITED STATES PATENTS von Frben Feb. 27, 1866 Judd May 24, 1932 Atwater Aug. 31, 1943 Moyer Apr. 11,1950

Kennedy Ian. 7, 1,958

FOREIGN PATENTS sardinia, yof 1856 

